Izimiso Zobuchwepheshe Nezinqubo Ze-LED Epitaxial Wafers

Kusukela kumgomo wokusebenza wama-LED, kuyabonakala ukuthi i-epitaxial wafer material iyingxenye eyinhloko ye-LED. Eqinisweni, amapharamitha angukhiye we-optoelectronic afana ne-wavelength, ukukhanya, ne-voltage eya phambili anqunywa kakhulu yi-epitaxial material. Ubuchwepheshe be-Epitaxial wafer kanye nemishini kubalulekile enqubweni yokukhiqiza, nge-Metal-Organic Chemical Vapor Deposition (MOCVD) okuyindlela eyinhloko yokukhulisa izingqimba ezincane zekristalu eyodwa ye-III-V, II-VI compounds, kanye nama-alloys azo. Ngezansi amanye amathrendi esikhathi esizayo kubuchwepheshe be-LED epitaxial wafer.

1. Ukuthuthukiswa Kwenqubo Yokukhula Kwezinyathelo Ezimbili

Njengamanje, ukukhiqizwa kwezentengiselwano kusebenzisa inqubo yokukhula enezinyathelo ezimbili, kodwa inani lama-substrates angalayishwa ngesikhathi esisodwa lilinganiselwe. Ngenkathi amasistimu angama-wafer ayi-6 esevuthiwe, imishini ephethe ama-wafer angama-20 isathuthukiswa. Ukwandisa inani lama-wafer ngokuvamile kuholela ekufaneni okunganele kuzindlalelo ze-epitaxial. Intuthuko yesikhathi esizayo izogxila ezindleleni ezimbili:

• Ukuthuthukisa ubuchwepheshe obuvumela ukulayisha ama-substrates amaningi ekamelweni elilodwa lokusabela, okuwenza afaneleke kakhulu ekukhiqizeni ngezinga elikhulu kanye nokwehliswa kwezindleko.
• Ithuthukela okokusebenza okuzenzakalelayo, okuphindaphindwayo kwe-single-wafer eyodwa.

2. I-Hydride Vapor Phase Epitaxy (HVPE) Technology

Lobu buchwepheshe buvumela ukukhula okusheshayo kwamafilimu awugqinsi ane-dislocation density ephansi, engasebenza njengama-substrates okukhula kwe-homoepitaxial kusetshenziswa ezinye izindlela. Ukwengeza, amafilimu e-GaN ahlukaniswe ne-substrate angase abe ezinye izindlela zama-chips e-GaN single-crystal chips. Kodwa-ke, i-HVPE inezihibe, njengobunzima bokulawula ukujiya okunembayo kanye namagesi okusabela okubola avimbela ukuthuthuka okuqhubekayo kokuhlanzeka kwezinto ze-GaN.

I-Si-doped HVPE-GaN

(a) Ukwakheka kwe-Si-doped HVPE-GaN reactor; (b) Isithombe sika-800 μm- ugqinsi lwe-Si-doped HVPE-GaN;

(c) Ukusatshalaliswa kokugxiliswa kwenkampani yenethiwekhi yamahhala ngobubanzi be-Si-doped HVPE-GaN

3. Ukukhula Kwe-Epitaxial Okukhethiwe noma Ubuchwepheshe Bokukhula Kwe-Epitaxial Emuva

Le nqubo ingaqhubeka nokunciphisa ukuminyana kokususwa futhi ithuthukise ikhwalithi yekristalu yezendlalelo ze-GaN epitaxial. Inqubo ibandakanya:

• Ukufaka ungqimba lwe-GaN ku-substrate efanelekile (isafire noma i-SiC).
• Kufakwa isendlalelo semaski se-polycrystalline SiO₂ ngaphezulu.
• Ukusebenzisa i-photolithography kanye ne-etching ukuze udale amawindi e-GaN nemicu yemaski ye-SiO₂.Ngesikhathi sokukhula okulandelayo, i-GaN iqala ikhule iqonde emafasiteleni bese ilandelana phezu kwemicu ye-SiO₂.

I-XKH's GaN-on-Sapphire wafer

4. I-Pendeo-Epitaxy Technology

Le ndlela inciphisa kakhulu ukukhubazeka kwe-lattice okubangelwa ukungafani kwe-lattice nokushisayo phakathi kwe-substrate ne-epitaxial layer, ithuthukisa nakakhulu ikhwalithi yekristalu ye-GaN. Izinyathelo zihlanganisa:

• Ukukhulisa ungqimba lwe-GaN epitaxial ku-substrate efanelekile (6H-SiC noma i-Si) kusetshenziswa inqubo yezinyathelo ezimbili.
• Yenza ukuqoshwa okukhethiwe kongqimba lwe-epitaxial phansi ku-substrate, kudala insika eshintshanayo (i-GaN/buffer/substrate) kanye nezakhiwo zemisele.
• Ukukhula kwezendlalelo ezengeziwe ze-GaN, ezinwebeka ngokucheleka ukusuka ezindongeni ezisemaceleni zezinsika zangempela ze-GaN, zilengiswa phezu kwemisele.Njengoba ingekho imaski esetshenziswayo, lokhu kugwema ukuthintana phakathi kwe-GaN nezinto zamaski.

I-wafer ye-XKH ye-GaN-on-Silicon

5. Ukuthuthukiswa kwe-Short-Wavelength UV LED Epitaxial Materials

Lokhu kubeka isisekelo esiqinile sama-LED amhlophe asuselwa ku-UV-phosphor. Ama-phosphor amaningi asebenza kahle kakhulu angajatshuliswa ukukhanya kwe-UV, anikeze ukukhanya okuphakeme okuphezulu kunohlelo lwamanje lwe-YAG:Ce, ngaleyo ndlela kuthuthukiswe ukusebenza kwe-LED emhlophe.

6. Multi-Quantum Well (MQW) Chip Technology

Ezakhiweni ze-MQW, ukungcola okuhlukene kwenziwa ngesikhathi sokukhula kongqimba olukhipha ukukhanya ukuze kwakhiwe imithombo ehlukahlukene ye-quantum. Ukuhlanganiswa kabusha kwama-photon aphuma kule mithombo kukhiqiza ukukhanya okumhlophe ngokuqondile. Le ndlela ithuthukisa ukusebenza kahle okukhanyayo, yehlisa izindleko, futhi yenza lula ukupakishwa nokulawulwa kwesekethe, nakuba iletha izinselele ezinkulu zobuchwepheshe.

7. Ukuthuthukiswa kobuchwepheshe be-"Photon Recycling".

NgoJanuwari 1999, iSumitomo yaseJapan yakha i-LED emhlophe isebenzisa impahla ye-ZnSe. Ubuchwepheshe bubandakanya ukukhulisa ifilimu elincanyana le-CdZnSe ku-ZnSe single-crystal substrate. Uma ifakwe ugesi, ifilimu ikhipha ukukhanya okuluhlaza okwesibhakabhaka, okusebenzisana ne-ZnSe substrate ukukhiqiza ukukhanya okuphuzi okuhambisanayo, okuholela ekukhanyeni okumhlophe. Ngokufanayo, Isikhungo Sokucwaninga Ngezithombe zaseBoston University sibeke inhlanganisela ye-AlInGaP semiconductor ku-GaN-LED eluhlaza okwesibhakabhaka ukuze kukhiqizwe ukukhanya okumhlophe.

8. Ukugeleza Kwenqubo Ye-Epitaxial Wafer Ye-LED

① I-Epitaxial Wafer Fabrication:
I-Substrate → Idizayini yesakhiwo → Ukukhula kwesendlalelo sebhafa → Ukukhula kongqimba lwe-GaN yohlobo lwe-N → ukukhula kwesendlalelo esikhipha ukukhanya kwe-MQW → Ukukhula kongqimba lwe-GaN lohlobo lwe-P → I-Annealing → Ukuhlola (i-photoluminescence, i-X-ray) → i-Epitaxial wafer

② Ukwakhiwa kwe-chip:
I-Epitaxial wafer → Ukwakhiwa kwemaski nokwenza → I-Photolithography → Ukufakwa kwe-ion → i-electrode yohlobo lwe-N (i-electrode yohlobo lwe-N (deposition, annealing, etching) → i-electrode yohlobo lwe-P (ukubeka, ukunamathisela, ukunamathisela) → Ukudayela → Ukuhlolwa kwe-chip nokugreda.

Iwafa ye-ZMSH ye-GaN-on-SiC